Bone
Osteosarcoma
Low grade intraosseous (central) osteosarcoma


Topic Completed: 1 April 2016

Revised: 28 December 2018

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PubMed Search: Central low-grade osteosarcoma

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Cite this page: Stockman, D.L. Low grade intraosseous (central) osteosarcoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/boneLGcentralosteo.html. Accessed December 15th, 2019.
Definition / general
  • Rare tumor (1% of osteosarcomas) with good prognosis
  • Develops during 2nd - 5th decades of life
  • Similar in histologic appearance to surface low grade osteosarcoma (parosteal osteosarcoma)
  • Metastatic rate ~ 15% due to tumors that have undergone dedifferentiation
Sites
  • Femur is most commonly affected, followed by tibia
  • Typically centered in medullary cavity of metaphysis or metaphyseal-diaphyseal region of long tubular bone
Radiology description
  • Poor margination with cortical disruption
  • Poorly demarcated margins with soft tissue extension
  • Variable matrix mineralization
Radiology images

Contributed by Dr. Mark R. Wick:

Distal femur

Treatment
  • En bloc resection
Gross description
  • Little to no necrosis, resembles a low grade bone forming lesion
  • Cut surface is hard, gritty, tan-white
  • Poorly defined margins, may show cortical destruction with associated soft tissue extension
Microscopic (histologic) description
  • Low grade osteosarcoma composed of bland spindle shaped cells and mature bone
  • Paucicellular, infiltrates between bone trabeculae composed of interlacing fascicles of spindle cells with mild atypia and rare mitotic figures in heavy collagenous background
  • Moderate osteoid and immature bone formation
Microscopic (histologic) images

Contributed by Dr. Mark R. Wick:

Various images

Positive stains
  • MDM2 positivity in 40% of cases, negative staining does not exclude osteosarcoma diagnosis, positive staining suggests malignancy
  • Must correlate with radiology and histology and get second opinion in these cases as treatment is resection
Differential diagnosis
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